David Cameron has approved a major retreat over aircraft for the Royal Navy’s
new carriers, abandoning plans to buy the conventional take-off version of
the F-35 Joint Strike Fighter.

Philip Hammond, the Defence Secretary, will tell MPs tomorrow that the Government will now purchase the jump-jet model of the plane instead, reversing one of the central decisions in the Coalition’s controversial defence review.

The Prime Minister’s National Security Council yesterday considered Mr Hammond’s plan, which will be announced to the House of Commons.

Mr Hammond will claim the decision will save hundreds of millions of pounds and help the Armed Forces. But he will face accusations of a climb-down driven by financial miscalculation.

The decision to buy the conventional take-off “C-variant” of the F-35 was at the heart of the Strategic Defence and Security Review in 2010.

Deploying the aircraft would require modifications to the new Queen Elizabeth-class aircraft carriers to install catapults and landing gear.

The Ministry of Defence originally estimated the cost of that work at around £400 million, but internal MoD projections now put the figure at closer to £2 billion.

Mr Hammond told The Daily Telegraph this week that, since the defence review, “the facts have changed” on the choice of planes for the new carriers.

Attempting to balance the defence budget after years of overspending, Mr Hammond yesterday told Cabinet ministers that the rising cost should lead to the catapult plan being abandoned.

The Daily Telegraph earlier this month disclosed a secret Ministry of Defence paper showing military planners considered the jump-jet to be less useful and powerful than the conventional variant.

Despite the embarrassment of overturning the decision, ministers will argue that the change could bring some military benefits to the UK. In particular, buying the jump-jet could mean the next generation of carriers is ready to sail

The decision to install catapults on the new carriers was expected to delay the arrival of the new vessels until at least 2020. Delays in completing the conventional variant plane could have pushed that date back to 2023 or even later, leaving the UK without a working aircraft carrier for at least a decade.

By contrast, the development of the jump-jet fighter is proceeding more smoothly than expected, meaning the aircraft could be ready to fly from the new carriers as early as 2018.

Adopting the jump-jet could also allow the Navy to have two operational carriers. Under the review, one of the new carriers is to be mothballed to save money.

Downing Street confirmed a statement on the carrier programme was imminent.